Marine elevator

ABSTRACT

A marine elevator having a U-shaped, pontoon supported, frame into which a vessel to be lifted is moved and a winch operated cable supported platform mounted for vertical movement within the frame for lifting the vessel clear of the water. Vertical supports carried by the platform support the vessel, when lifted, in an upright position.

MARINE ELEVATOR BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to marine elevators or dry docks for raising vessels.

2. Prior Art I In many dry docks piles are used to support a vertically moveable platform which can be raised or lowered by known gear to lift the vessel clear of the water.

This type of dry dock or marine elevator has certain SUMMARY OF THE INVENTION The present invention provides a marine elevator which is highly transportable as it does not depend uponpilings for support and which is easy and safe to operate as it does not depend on transfer of water into and out of pontoons to obtain vertical movement.

The marine elevator of the present invention includes a pontoon supported U-shaped frame having an end member and opposite side members into which a floating vessel can be manoeuvered, a vertically moveable platform disposed within the frame, adjustable side supports of the platform adapted to be positioned into engagement with the vessel. A winch mounted on the end member of the frame and cables connected to the platform and operated by the winch for lifting and lowering the platform so as to raise and lower the vessel.

A detailed description following related to drawings gives exemplification of preferred embodiment of the invention which-however, is capable of expression in a structure other than that particularly described and illustrated.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective showing a marine elevator according to the invention, parts being broken away for clarity of illustration,

FIG. 2 is a plan view of a supporting frame of the invention,

FIG. 3 is an elevation of a side support,

FIG. 4 is a plan view of the side support shown in FIG. 3.

DETAILED DESCRIPTION FIGS. 1 and 2 Referring to FIG. 1 a marine elevator according to the invention, designated generally 10, supports a vessel 11, shown in broken outline, raised clear of the water. The elevator has a rigid main frame 12 which is generally U-shaped having side members 13 and 14 and an end member 15. The side members of the main frame are supported by supporting pontoons, severally 16, three beneath each member. A fixed floatation pontoon 18 having a top wall 18.1 which is spaced below top walls of the supporting pontoon 16 by a distance D is mounted beneath the end member 15.

Brackets 19 are used to connect the main frame and the pontoons. I

The elevator has a vertically moveable platform 21, shown in solid outline in a raised position and in broken outline 21.1 in a lowered position. The platform is supported on a structural steel framework generally 23 which has longitudinally disposed frame members 24 extending between a front transverse member 25 and a rear transverse member 26.

Four vertical posts 27, 28, 29, and 31 extend upwards from ends of the front and rear transverse members. The posts 27 and 28 are connected by a horizontal strut 32 and the posts 29 and 31 are likewise connected by a horizontal strut 33. The posts carry, at upper ends, supporting brackets generally 34, 35, 36, and 37 which are adapted to be positioned against gunwhales of the vessel for holding the vessel in an upright position when it is lifted.

FIGS. 3 and 4 FIGS. 3 and 4 show one of the supporting brackets 34. The supporting bracket 34 includes a pair of vertically spaced telescopically extensible and retractable struts 38 and 39 which are maintained in spaced parallel relationship by vertical and diagonal braces 41 and 42. The struts 38 and 39 have hinge connections at 43 and 44 at inner ends with the post 27 and carry, at outer ends, a vertically extending padded buffer 45. The struts 38, 39 are fixed in adjusted positions of extension and retraction by locking pins 47.

A pair of diagonal braces 48 have hinged connections 49 adjacent outer ends of the telescopic struts 38 and 39 and having a hinged connection 49.1 at opposite ends with the collar 50 mounted for slidable movement on the horizontal strut 32. The collar is releasably and adjustably secured on the strut 32 by a locking pin 51. FIGS. 1 and 2 Vertical movement of the platform is effected by operation of a hoist assembly generally 60. The hoist assembly includes a two drum winch 61 having drums 61.1 and 61.2 mounted on the end member 15 of the main frame and is driven through a drive shaft 62 connected through suitable reversible controls, not shown, to a driving motor 63. A cable 64 wound on the drum 61.1 extends around a horizontal sheave 65 mounted on the end frame member 15, thence along the side frame member 13, thence over a vertical sheave 66 mounted on the side frame member 13 adjacent the post 27 andthen vertically downwards and around a vertical sheave 67 mounted in a bracket 68 at one end 25.1 of the transverse frame member 25, thence vertically upwards and secured at free end 69 to the side frame member 13.

A cable 71 wound on the drum 61.2 is connected in a manner as described with reference to cable 64 to one end 26.1 of therear transverse member 26. Opposite ends of the rear and front transverse members are connected by cables 72 and 73 in a similar manner to the drums 61.1 and 61.2. The end 26.1 of the rear transverse member 26, and opposite ends of side transverse members also have brackets similar to the bracket 68. The cables are so wound on respective drums that on operation of the winch 61 all cables are moved simultaneously and by an equal amount so that the platform remains level as it is lifted or lowered.

The brackets 68 project above the side frame members when the platform is fully elevated and have registering holes 76 through which short rods 77 can be extended. It is seen that this provides a positive lock independent of the cables so that when the platform is fully elevated the rods 77 can be inserted then the platform lowered until the rods rest upon frames so as to take the weight off the cables.

PONTOON ARRANGEMENT The pontoon 18 beneath the end frame member has been described as being a fixed floatation." This term is used to indicate that, in an unloaded condition of the elevator, the top wall 18.1 is just awash having sufficient bouyancy only to carry the dead weight of the winch and the end frame member 15. Thus in an unloaded condition the elevator floats with the side and end members of the U-shaped main frame horizontal. It is to be understood that the size and bouyancy of the elevator are such that presence of, for instance, workmen on any part of the elevator will not cause material departure from level horizontal floatation.

OPERATION When unloaded, the marine elevator 10, which is normally anchored in place, floats level as has been explained.

To operate the elevator the platform is lowered to the broken outline position 21.1 so as to permit the vessel 11 to enter the main frame between the side members 13 and 14. The unloaded elevator has a metacenter which, in plan, is central of a longitudinal axis of the elevator so that a vertical load applied to pass through the metacenter will cause the elevator to move evenly downwards, maintaining its trim, by an amount according to the total bouyancy and the load applied. The fixed floatation pontoon is just awash in an unloaded position so that its bouyant force remains unchanged regardless of depth to which the pontoon is submerged. The elevator is designed so that, with contemplated loads it will not submerge a distance greater than D so that the main frame always remains above water.

The vessel, position of center of gravity of which is known, is entered centrally between the side members 13 and 14 until the center of gravity of the vessel is in the proper position, namely half way down the side members. Gauge, or sighting marks, (not shown) can be placed on the side members of the main frame to facilitate positioning. The winch is then operated to raise the platform until the keel of the vessel is in contact with the platform. The supporting brackets 34, 35, 36, and 37 are then suitably adjusted to bear against the gunwhales of the vessel and the winch is then operated to raise the platform to its upper position. 21. In this position the platform is clear of the water and the vessel can be worked upon.

If, due to improper longitudinal positioning of the vessel, uneven settling of the marine elevator occurs the elevator can be lowered to allow the vessel to be repositioned.

Ordinarily there is no particular difficulty in properly positioning a vessel however, in some circumstances, e.g., overlength vessels, where the vessel cannot be positioned so that its center of gravity is half way down the side members, the main frame can be trimmed to a level position by injection of water into an appropriate pair of pontoons. Pumps which can be used for this purpose are not shown.

I claim:

1. A marine elevator apparatus including:

a. a U-shaped main frame having spaced side members and a connecting end member,

b. pontoons beneath the side and end member of frame for supporting the latter above water,

c. a vessel lifting platform disposed between the side members of the main frame for vertical movement,

d. vertical posts disposed in fore and aft pairs and secured at lower ends to the platform and extending upwards through and above the side members of the U-shaped frame,

e. a winch mounted on the end member of the main frame,

f. hoisting cables extending from the winch and connected to the platform operable for lifting and low ering the platform between elevated and lowered positions when the winch is operated,

g. supporting means mounted at upper ends of the posts engageable with sides of a vessel to be lifted for supporting the vessel in an upright position when the platform is elevated.

2.Marine elevator apparatus as claimed in claim 1 in which the pontoons supporting the end frame member are just awash when the elevator is in an unloaded condition.

3. Marine elevator apparatus as claimed in claim 1 in which the means for supporting the vessel in an upright position includes:

a. a strut extending longitudinally between each pair of fore and aft posts,

b. a telescopically extensible and retractable supporting bracket swingably mounted at an upper end of each post,

c. a collar mounted on the strut adjacent each post for longitudinal adjustment of the strut,

d. angle braces having a hinged connection with each bracket and associated collar to enable angular adjustment of each bracket.

4. Marine elevator apparatus as claimed in claim 1 including a locking bracket mounted on the platform at each post adapted to extend upwards above the main frame when the platform is raised to a fully elevated position and a rod slidable transversely through each locking bracket for supporting the platform in an elevated condition on the main frame when the cables are slackened off.

5. Marine elevator apparatus as claimed in claim 1 in which each side member of the main frame is supported by a plurality of longitudinally spaced pontoons, at least one pontoon of each side member being adapted to receive measured amounts of water so as to enable longitudinal trimming of the elevator apparatus.

6. Marine elevator apparatus as claimed in claim 1 which platform has longitudinally spaced front and rear transverse members at opposite ends of which the posts are secured and a vertical sheave mounted for rotation at each end of said transverse members. 

1. A marine elevator apparatus including: a. a U-shaped main frame having spaced side members and a connecting end member, b. pontoons beneath the side and end member of frame for supporting the latter above water, c. a vessel lifting platform disposed between the side members of the main frame for vertical movement, d. vertical posts disposed in fore and aft pairs and secured at lower ends to the platform and extending upwards through and above the side members of the U-shaped frame, e. a winch mounted on the end member of the main frame, f. hoisting cables extending from the winch and connected to the platform operable for lifting and lowering the platform between elevated and lowered positions when the winch is operated, g. supporting means mounted at upper ends of the posts engageable with sides of a vessel to be lifted for supporting the vessel in an upright position when the platform is elevated.
 2. Marine elevator apparatus as claimed in claim 1 in which the pontoons supporting the end frame member are just awash when the elevator is in an unloaded condition.
 3. Marine elevator apparatus as claimed in claim 1 in which the means for supporting the vessel in an upright position includes: a. a strut extending longitudinally between each pair of fore and aft posts, b. a telescopically extensible and retractable supporting bracket swingably mounted at an upper end of each post, c. a collar mounted on the strut adjacent each post for longitudinal adjustment of the strut, d. angle braces having a hInged connection with each bracket and associated collar to enable angular adjustment of each bracket.
 4. Marine elevator apparatus as claimed in claim 1 including a locking bracket mounted on the platform at each post adapted to extend upwards above the main frame when the platform is raised to a fully elevated position and a rod slidable transversely through each locking bracket for supporting the platform in an elevated condition on the main frame when the cables are slackened off.
 5. Marine elevator apparatus as claimed in claim 1 in which each side member of the main frame is supported by a plurality of longitudinally spaced pontoons, at least one pontoon of each side member being adapted to receive measured amounts of water so as to enable longitudinal trimming of the elevator apparatus.
 6. Marine elevator apparatus as claimed in claim 1 which platform has longitudinally spaced front and rear transverse members at opposite ends of which the posts are secured and a vertical sheave mounted for rotation at each end of said transverse members. 